In September of 2015, Harvey Fierstein said he was going to be a replacement for someone in a show. We could not say cause it was not official yet. I thought he might Nathan Lane it "It's Only a Play" but that turned out to be Martin Sheen.
Cloris Leachman was announced to take over for Andrea Martin in YOUNG FRANKENSTEIN. She did the original workshops/readings, but Mel thought the Broadway run would be too strenuous on such an old lady... Then Cloris went on to kill it in Dancing With the Stars, and Mel changed his mind. Not to mention the show wasn't doing so hot... They announced her casting in Nov.-Dec.ish, and the show closed after the New Year before Cloris could begin. Too bad, would have loved to see her deliver "He Vas My Boyfriend".
Meat Loaf, who normally turns down musicals as a rule (still does), was in talks to play the Child Catcher in Chitty Chitty Bang Bang, but according to a BroadwayWorld interview about eleven years ago, it fell apart due to creative differences with the director:
"... we talked about me doing the Child Catcher. It would have been a real change in type for them. I thought about it for a long time, because it was an interesting piece and I had a certain way that I wanted to do it. I got on the phone with the director, and I was talking to him and I said, 'You blocked it and staged it a certain way in London, but this is what I'm thinking because I wasn't particularly fond of it. I don't think he was scary enough, I don't think he was intense enough. I don't think that... the way he was handled... that you were getting the chills enough.' So, I was describing to him how I wanted to do it when the director said, 'Well, that's nice, we'll see.' I went okay, I'm not doing it, because I knew what it meant. It's like when a kid asks, 'Daddy, can I have ice cream?' and the dad says, 'Oh Billy, we'll see.' What does that mean? No! And when he said, 'That's not a bad idea, we'll see when we get to rehearsal,' I knew that he meant he was going to do it his way, and we'd wind up having a big fight, so there was no reason to go through the aggravation."
Reportedly Meat's ideas including going into the audience and menacing kiddies in the house to produce the desired chills. As a producer myself, I can see the liability suits from a mile away; I wouldn't sign off on it either.